The present invention is directed to a display apparatus including a data driver. More particularly, the present invention is directed to a display apparatus including a data driver capable of removing slew rate difference among a plurality of output buffers.
A Liquid Crystal Display (LCD) apparatus, which is one of a family of flat panel display apparatuses, has advantages of being smaller, lighter, shorter, thinner, and a consumer of less power. Recently, the LCD has been used widely in laptop computers, television sets, and mobile phones, among other devices.
In general, an LCD apparatus includes an LCD panel, which displays an image. A data driver and a gate driver drive the LCD panel. An LCD panel includes data lines, which receive a data voltage from the data driver, and gate lines, which receive a gate voltage from the gate driver. Pixel domains are defined in the LCD panel by the data lines and the gate lines. A pixel, which includes a thin film transistor (TFT) and pixel electrode, is arranged in each of the pixel domains. The data driver and the gate driver include chips to be mounted on the LCD panel or on separate films.
The data driver includes output buffers, which are coupled to the data lines in one-to-one correspondence, and buffers data voltage transmitted from a D/A converter to provide the data voltage buffered to the data lines. As described above, since the data voltage which drives each pixel of the LCD panel is output through the output buffers, characteristics of the output buffers may have a significant effect on a display quality of the LCD apparatus. The parameters that determine the characteristics of the output buffers are, for example, slew rate, gain, and phase margin.
The slew rate of the output buffers is an especially important factor that determines the display quality of the LCD apparatus. In other words, when a slew rate difference occurs among the output buffers and among the chips that constitute a data driver, vertical lines appear at a boundary portion between the output buffers and the chips where the slew rate difference occurs, which deteriorates the display quality of the LCD apparatus.